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How Reno Racers Keep Their Cool

At the Reno air races, pilots know that to go fast, you have to stay cool. That’s where Pete Law comes in.

Since 1966, thermodynamics engineer Pete Law has been showing up at the National Championship Air Races in Reno, Nevada, with his toolbox and a career’s worth of knowledge about cooling systems.
(Dan Whitney)

“Jeez, I’m going to have to think about this.” Law rummages through an omnipresent briefcase. “I have a chart that shows horsepower versus rpm, and it shows deriched and non-deriched fuel flows. It’s in here somewhere.”

Despite his expertise with long-obsolete piston engines, Law had never so much as seen a warbird when he hired on at Lockheed in 1959. He started working on the engineering environmental control systems on the F-104G and enjoyed the challenge. After two years devoted to Mach 2 Starfighters, he got another assignment. “Everybody on the ‘white’ [non-classified] side of the company dreamed of being ‘borrowed’ by Ben Rich to work at the Skunk Works,” Law recalls. “In 1961, he ‘borrowed’ me for six months, and I stayed for 40 years.”

Law’s first assignment was structural thermal analysis of the A-12, the Central Intelligence Agency’s single-seat predecessor to the SR-71 Blackbird. Flying at Mach 3.2, the A-12 reached temperatures up to 1,000 degrees Fahrenheit, posing thermodynamics issues that aeronautical engineers had never faced. Rich, a thermodynamicist himself, was a mentor to Law and in 1980, a few years after Rich succeeded aviation icon Kelly Johnson as chief of the Skunk Works, he tapped Law to head the thermodynamics department. Long before that, though, Rich had triggered a watershed event in Law’s other career.

In the fall of 1964, Rich introduced Law to Lockheed test pilot Darryl Greenamyer. In addition to testing the A-12, Greenamyer had just flown his own Grumman F8F Bearcat in the inaugural air races at Reno. He was looking for more speed, and he thought Law could help him find it by revisiting a concept that the Germans had used on the record-setting pre-war Messerschmitt Me 209.

In the F-104, air passes through a heat exchanger submerged in water. The water cools the air for air conditioning in the cockpit before boiling off into steam. Greenamyer wanted to use a similar boil-off system in his Bearcat. Only instead of cooling air, he wanted to cool engine oil, just as the Me 209 had done. By bathing the oil cooler in a cold fluid, Greenamyer figured he could get rid of the two scoops in the airplane’s wings designed to provide cold air to the system. Eliminating the air scoops would reduce some aerodynamic inefficiency known as cooling drag.

Law immediately understood the concept of boil-off cooling, but he knew nothing about piston-engine aircraft. Luckily, Bruce Boland, a structural engineer he’d befriended on his first day at the Skunk Works, was a warbird fanatic. “He ate, slept, and dreamed old airplanes, especially Grummans,” Law says. “He was intimately familiar with them, and it was his lifelong dream to work on them. His hero airplane was the Bearcat.” The two formed a partnership.

Law engineered the boiler system, but instead of using water, he used ADI fluid—a 50-50 mix of water and methanol—because it cooled the oil to a lower temperature than water alone. (The unit reduced cooling drag so well that the resulting gain in airspeed was the equivalent of giving the engine an additional 200 horsepower.) Meanwhile, Boland upgraded the aerodynamic qualities of the airplane by slicking up the airframe. Flying the modified Bearcat, Greenamyer blitzed the Unlimited competition at Reno in 1965. And 1966. And 1967. And 1968. In August 1969, he flew the Bearcat to a world speed record of 483 mph. (The Fédération Aéronautique Internationale later re-calculated the speed to 482.464 mph, but the recalculation had no impact on the record.) A month later, he lapped the entire field at Reno. With nobody left to beat, Greenamyer told Law, “You and Bruce have to go off and start helping the other guys.”

His suggestion was not quite as altruistic as it sounds. Greenamyer knew that racers, fans, and, most important of all, sponsors would lose interest if the same guy won all the time. For the races to survive, they had to be competitive.